Hydrocarbon gas processing featuring a compressed reflux stream formed by combining a portion of column residue gas with a distillation vapor stream withdrawn from the side of the column

ABSTRACT

A process and an apparatus are disclosed for the recovery of ethane, ethylene, propane, propylene, and heavier hydrocarbon components from a hydrocarbon gas stream. The stream is cooled and divided into first and second streams. The first stream is further cooled to condense substantially all of it and divided into first and second portions. The first and second portions are expanded to the fractionation tower pressure and supplied to the fractionation tower at upper mid-column feed positions, with the expanded second portion being heated before it enters the tower. The second stream is expanded to the tower pressure and supplied to the column at a mid-column feed position. A distillation vapor stream is withdrawn from the column above the feed point of the second stream, combined with a portion of the tower overhead vapor stream, compressed to higher pressure, and directed into heat exchange relation with the remaining tower overhead vapor stream and the expanded second portion to cool the compressed combined vapor stream and condense at least a part of it, forming a condensed stream. At least a portion of the condensed stream is expanded to the tower pressure and directed to the fractionation tower as its top feed. The quantities and temperatures of the feeds to the fractionation tower are effective to maintain the overhead temperature of the fractionation tower at a temperature whereby the major portion of the desired components is recovered.

This invention relates to a process and an apparatus for the separationof a gas containing hydrocarbons. The applicants claim the benefitsunder Title 35, United States Code, Section 119(e) of prior U.S.Provisional Applications No. 61/244,181 which was filed on Sep. 21,2009, No. 61/346,150 which was filed on May 19, 2010, and No. 61/351,045which was filed on Jun. 3, 2010.

BACKGROUND OF THE INVENTION

Ethylene, ethane, propylene, propane, and/or heavier hydrocarbons can berecovered from a variety of gases, such as natural gas, refinery gas,and synthetic gas streams obtained from other hydrocarbon materials suchas coal, crude oil, naphtha, oil shale, tar sands, and lignite. Naturalgas usually has a major proportion of methane and ethane, i.e., methaneand ethane together comprise at least 50 mole percent of the gas. Thegas also contains relatively lesser amounts of heavier hydrocarbons suchas propane, butanes, pentanes, and the like, as well as hydrogen,nitrogen, carbon dioxide, and other gases.

The present invention is generally concerned with the recovery ofethylene, ethane, propylene, propane and heavier hydrocarbons from suchgas streams. A typical analysis of a gas stream to be processed inaccordance with this invention would be, in approximate mole percent,90.5% methane, 4.1% ethane and other C₂ components, 1.3% propane andother C₃ components, 0.4% iso-butane, 0.3% normal butane, and 0.5%pentanes plus, with the balance made up of nitrogen and carbon dioxide.Sulfur containing gases are also sometimes present.

The historically cyclic fluctuations in the prices of both natural gasand its natural gas liquid (NGL) constituents have at times reduced theincremental value of ethane, ethylene, propane, propylene, and heaviercomponents as liquid products. This has resulted in a demand forprocesses that can provide more efficient recoveries of these products,for processes that can provide efficient recoveries with lower capitalinvestment, and for processes that can be easily adapted or adjusted tovary the recovery of a specific component over a broad range. Availableprocesses for separating these materials include those based uponcooling and refrigeration of gas, oil absorption, and refrigerated oilabsorption. Additionally, cryogenic processes have become popularbecause of the availability of economical equipment that produces powerwhile simultaneously expanding and extracting heat from the gas beingprocessed. Depending upon the pressure of the gas source, the richness(ethane, ethylene, and heavier hydrocarbons content) of the gas, and thedesired end products, each of these processes or a combination thereofmay be employed.

The cryogenic expansion process is now generally preferred for naturalgas liquids recovery because it provides maximum simplicity with ease ofstartup, operating flexibility, good efficiency, safety, and goodreliability. U.S. Pat. Nos. 3,292,380; 4,061,481; 4,140,504; 4,157,904;4,171,964; 4,185,978; 4,251,249; 4,278,457; 4,519,824; 4,617,039;4,687,499; 4,689,063; 4,690,702; 4,854,955; 4,869,740; 4,889,545;5,275,005; 5,555,748; 5,566,554; 5,568,737; 5,771,712; 5,799,507;5,881,569; 5,890,378; 5,983,664; 6,182,469; 6,578,379; 6,712,880;6,915,662; 7,191,617; 7,219,513; reissue U.S. Pat. No. 33,408; andco-pending application Ser. Nos. 11/430,412; 11/839,693; 11/971,491;12/206,230; 12/689,616; 12/717,394; 12/750,862; 12/772,472; and12/781,259 describe relevant processes (although the description of thepresent invention in some cases is based on different processingconditions than those described in the cited U.S. patents).

In a typical cryogenic expansion recovery process, a feed gas streamunder pressure is cooled by heat exchange with other streams of theprocess and/or external sources of refrigeration such as a propanecompression-refrigeration system. As the gas is cooled, liquids may becondensed and collected in one or more separators as high-pressureliquids containing some of the desired C₂+ components. Depending on therichness of the gas and the amount of liquids formed, the high-pressureliquids may be expanded to a lower pressure and fractionated. Thevaporization occurring during expansion of the liquids results infurther cooling of the stream. Under some conditions, pre-cooling thehigh pressure liquids prior to the expansion may be desirable in orderto further lower the temperature resulting from the expansion. Theexpanded stream, comprising a mixture of liquid and vapor, isfractionated in a distillation

-   -   (demethanizer or deethanizer) column. In the column, the        expansion cooled stream(s) is (are) distilled to separate        residual methane, nitrogen, and other volatile gases as overhead        vapor from the desired C₂ components, C₃ components, and heavier        hydrocarbon components as bottom liquid product, or to separate        residual methane, C₂ components, nitrogen, and other volatile        gases as overhead vapor from the desired C₃ components and        heavier hydrocarbon components as bottom liquid product.

If the feed gas is not totally condensed (typically it is not), thevapor remaining from the partial condensation can be split into twostreams. One portion of the vapor is passed through a work expansionmachine or engine, or an expansion valve, to a lower pressure at whichadditional liquids are condensed as a result of further cooling of thestream. The pressure after expansion is essentially the same as thepressure at which the distillation column is operated. The combinedvapor-liquid phases resulting from the expansion are supplied as feed tothe column.

The remaining portion of the vapor is cooled to substantial condensationby heat exchange with other process streams, e.g., the coldfractionation tower overhead. Some or all of the high-pressure liquidmay be combined with this vapor portion prior to cooling. The resultingcooled stream is then expanded through an appropriate expansion device,such as an expansion valve, to the pressure at which the demethanizer isoperated. During expansion, a portion of the liquid will vaporize,resulting in cooling of the total stream. The flash expanded stream isthen supplied as top feed to the demethanizer. Typically, the vaporportion of the flash expanded stream and the demethanizer overhead vaporcombine in an upper separator section in the fractionation tower asresidual methane product gas. Alternatively, the cooled and expandedstream may be supplied to a separator to provide vapor and liquidstreams. The vapor is combined with the tower overhead and the liquid issupplied to the column as a top column feed.

In the ideal operation of such a separation process, the residue gasleaving the process will contain substantially all of the methane in thefeed gas with essentially none of the heavier hydrocarbon components,and the bottoms fraction leaving the demethanizer will containsubstantially all of the heavier hydrocarbon components with essentiallyno methane or more volatile components. In practice, however, this idealsituation is not obtained because the conventional demethanizer isoperated largely as a stripping column. The methane product of theprocess, therefore, typically comprises vapors leaving the topfractionation stage of the column, together with vapors not subjected toany rectification step. Considerable losses of C₂, C₃, and C₄+components occur because the top liquid feed contains substantialquantities of these components and heavier hydrocarbon components,resulting in corresponding equilibrium quantities of C₂ components, C₃components, C₄ components, and heavier hydrocarbon components in thevapors leaving the top fractionation stage of the demethanizer. The lossof these desirable components could be significantly reduced if therising vapors could be brought into contact with a significant quantityof liquid (reflux) capable of absorbing the C₂ components, C₃components, C₄ components, and heavier hydrocarbon components from thevapors.

In recent years, the preferred processes for hydrocarbon separation usean upper absorber section to provide additional rectification of therising vapors. The source of the reflux stream for the upperrectification section is typically a recycled stream of residue gassupplied under pressure. The recycled residue gas stream is usuallycooled to substantial condensation by heat exchange with other processstreams, e.g., the cold fractionation tower overhead. The resultingsubstantially condensed stream is then expanded through an appropriateexpansion device, such as an expansion valve, to the pressure at whichthe demethanizer is operated. During expansion, a portion of the liquidwill usually vaporize, resulting in cooling of the total stream. Theflash expanded stream is then supplied as top feed to the demethanizer.Typically, the vapor portion of the expanded stream and the demethanizeroverhead vapor combine in an upper separator section in thefractionation tower as residual methane product gas. Alternatively, thecooled and expanded stream may be supplied to a separator to providevapor and liquid streams, so that thereafter the vapor is combined withthe tower overhead and the liquid is supplied to the column as a topcolumn feed. Typical process schemes of this type are disclosed in U.S.Pat. Nos. 4,889,545; 5,568,737; and 5,881,569, assignee's co-pendingapplication Ser. No. 12/717,394, and in Mowrey, E. Ross, “Efficient,High Recovery of Liquids from Natural Gas Utilizing a High PressureAbsorber”, Proceedings of the Eighty-First Annual Convention of the GasProcessors Association, Dallas, Tex., Mar. 11-13, 2002. These processesuse a compressor to provide the motive force for recycling the refluxstream to the demethanizer, adding to both the capital cost and theoperating cost of facilities using these processes.

The present invention also employs an upper rectification section (or aseparate rectification column if plant size or other factors favor usingseparate rectification and stripping columns). However, the refluxstream for this rectification section is provided by using a side drawof the vapors rising in a lower portion of the tower combined with aportion of the column overhead vapor. Because of the relatively highconcentration of C₂ components in the vapors lower in the tower, asignificant quantity of liquid can be condensed from this combined vaporstream with only a modest elevation in pressure, using the refrigerationavailable in the remaining portion of the cold overhead vapor leavingthe upper rectification section of the column to provide most of thecooling. This condensed liquid, which is predominantly liquid methane,can then be used to absorb C₂ components, C₃ components, C₄ components,and heavier hydrocarbon components from the vapors rising through theupper rectification section and thereby capture these valuablecomponents in the bottom liquid product from the demethanizer.

Heretofore, compressing either a portion of the cold overhead vaporstream or compressing a side draw vapor stream to provide reflux for theupper rectification section of the column has been employed in C₂+recovery systems, as illustrated in assignee's U.S. Pat. No. 4,889,545and assignee's co-pending application Ser. No. 11/839,693, respectively.Surprisingly, applicants have found that combining a portion of the coldoverhead vapor with the side draw vapor stream and then compressing thecombined stream improves the system efficiency while reducing operatingcost.

In accordance with the present invention, it has been found that C₂recovery in excess of 84% and C₃ and C₄+ recoveries in excess of 99% canbe obtained. In addition, the present invention makes possibleessentially 100% separation of methane and lighter components from theC₂ components and heavier components at lower energy requirementscompared to the prior art while maintaining the recovery levels. Thepresent invention, although applicable at lower pressures and warmertemperatures, is particularly advantageous when processing feed gases inthe range of 400 to 1500 psia [2,758 to 10,342 kPa(a)] or higher underconditions requiring NGL recovery column overhead temperatures of −50°F. [−46° C.] or colder.

For a better understanding of the present invention, reference is madeto the following examples and drawings. Referring to the drawings:

FIG. 1 is a flow diagram of a prior art natural gas processing plant inaccordance with assignee's co-pending application Ser. No. 11/839,693;

FIG. 2 is a flow diagram of a natural gas processing plant in accordancewith the present invention; and

FIGS. 3 through 6 are flow diagrams illustrating alternative means ofapplication of the present invention to a natural gas stream.

In the following explanation of the above figures, tables are providedsummarizing flow rates calculated for representative process conditions.In the tables appearing herein, the values for flow rates (in moles perhour) have been rounded to the nearest whole number for convenience. Thetotal stream rates shown in the tables include all non-hydrocarboncomponents and hence are generally larger than the sum of the streamflow rates for the hydrocarbon components. Temperatures indicated areapproximate values rounded to the nearest degree. It should also benoted that the process design calculations performed for the purpose ofcomparing the processes depicted in the figures are based on theassumption of no heat leak from

-   -   (or to) the surroundings to (or from) the process. The quality        of commercially available insulating materials makes this a very        reasonable assumption and one that is typically made by those        skilled in the art.

For convenience, process parameters are reported in both the traditionalBritish units and in the units of the Système International d'Unités(SI). The molar flow rates given in the tables may be interpreted aseither pound moles per hour or kilogram moles per hour. The energyconsumptions reported as horsepower (HP) and/or thousand British ThermalUnits per hour (MBTU/Hr) correspond to the stated molar flow rates inpound moles per hour. The energy consumptions reported as kilowatts (kW)correspond to the stated molar flow rates in kilogram moles per hour.

DESCRIPTION OF THE PRIOR ART

FIG. 1 is a process flow diagram showing the design of a processingplant to recover C₂+ components from natural gas using prior artaccording to assignee's co-pending application Ser. No. 11/839,693. Inthis simulation of the process, inlet gas enters the plant at 120° F.[49° C.] and 1025 psia [7,067 kPa(a)] as stream 31. If the inlet gascontains a concentration of sulfur compounds which would prevent theproduct streams from meeting specifications, the sulfur compounds areremoved by appropriate pretreatment of the feed gas (not illustrated).In addition, the feed stream is usually dehydrated to prevent hydrate(ice) formation under cryogenic conditions. Solid desiccant hastypically been used for this purpose.

The feed stream 31 is cooled in heat exchanger 10 by heat exchange withcool residue gas (stream 41 b), demethanizer reboiler liquids at 51° F.[11° C.] (stream 44), demethanizer lower side reboiler liquids at 10° F.[−12° C.] (stream 43), and demethanizer upper side reboiler liquids at−65° F. [−54° C.] (stream 42). Note that in all cases exchanger 10 isrepresentative of either a multitude of individual heat exchangers or asingle multi-pass heat exchanger, or any combination thereof. (Thedecision as to whether to use more than one heat exchanger for theindicated cooling services will depend on a number of factors including,but not limited to, inlet gas flow rate, heat exchanger size, streamtemperatures, etc.) The cooled stream 31 a enters separator 11 at −38°F. [−39° C.] and 1015 psia [6,998 kPa(a)] where the vapor (stream 32) isseparated from the condensed liquid (stream 33). The separator liquid(stream 33) is expanded to the operating pressure (approximately 465psia [3,208 kPa(a)]) of fractionation tower 18 by expansion valve 17,cooling stream 33 a to −67° F. [−55° C.] before it is supplied tofractionation tower 18 at a lower mid-column feed point.

The vapor (stream 32) from separator 11 is divided into two streams, 36and 39. Stream 36, containing about 23% of the total vapor, passesthrough heat exchanger 12 in heat exchange relation with the coldresidue gas (stream 41 a) where it is cooled to substantialcondensation. The resulting substantially condensed stream 36 a at −102°F. [−74° C.] is then flash expanded through expansion valve 14 toslightly above the operating pressure of fractionation tower 18. Duringexpansion a portion of the stream is vaporized, resulting in cooling ofthe total stream. In the process illustrated in FIG. 1, the expandedstream 36 b leaving expansion valve 14 reaches a temperature of −127° F.[−88° C.] before it is supplied at an upper mid-column feed point, inabsorbing section 18 a of fractionation tower 18.

The remaining 77% of the vapor from separator 11 (stream 39) enters awork expansion machine 15 in which mechanical energy is extracted fromthis portion of the high pressure feed. The machine 15 expands the vaporsubstantially isentropically to the tower operating pressure, with thework expansion cooling the expanded stream 39 a to a temperature ofapproximately −101° F. [−74° C.]. The typical commercially availableexpanders are capable of recovering on the order of 80-85% of the worktheoretically available in an ideal isentropic expansion. The workrecovered is often used to drive a centrifugal compressor (such as item16) that can be used to re-compress the residue gas (stream 41 c), forexample. The partially condensed expanded stream 39 a is thereaftersupplied as feed to fractionation tower 18 at a mid-column feed point.

The demethanizer in tower 18 is a conventional distillation columncontaining a plurality of vertically spaced trays, one or more packedbeds, or some combination of trays and packing. The demethanizer towerconsists of two sections: an upper absorbing (rectification) section 18a that contains the trays and/or packing to provide the necessarycontact between the vapor portions of the expanded streams 36 b and 39 arising upward and cold liquid falling downward to condense and absorbthe C₂ components, C₃ components, and heavier components; and a lower,stripping section 18 b that contains the trays and/or packing to providethe necessary contact between the liquids falling downward and thevapors rising upward. The demethanizing section 18 b also includes oneor more reboilers (such as the reboiler and side reboilers describedpreviously) which heat and vaporize a portion of the liquids flowingdown the column to provide the stripping vapors which flow up the columnto strip the liquid product, stream 45, of methane and lightercomponents. Stream 39 a enters demethanizer 18 at an intermediate feedposition located in the lower region of absorbing section 18 a ofdemethanizer 18. The liquid portion of the expanded stream 39 acommingles with liquids falling downward from absorbing section 18 a andthe combined liquid continues downward into stripping section 18 b ofdemethanizer 18. The vapor portion of the expanded stream 39 a risesupward through absorbing section 18 a and is contacted with cold liquidfalling downward to condense and absorb the C₂ components, C₃components, and heavier components.

A portion of the distillation vapor (stream 48) is withdrawn from anintermediate region of absorbing section 18 a in fractionation column18, above the feed position of expanded stream 39 a and below the feedposition of expanded stream 36 b. The distillation vapor stream 48 at−113° F. [−81° C.] is compressed to 604 psia [4,165 kPa(a)] (stream 48a) by reflux compressor 21, then cooled from −84° F. [−65° C.] to −124°F. [−87° C.] and substantially condensed (stream 48 b) in heat exchanger22 by heat exchange with cold residue gas stream 41, the overhead streamexiting the top of demethanizer 18. The substantially condensed stream48 b is then expanded through an appropriate expansion device, such asexpansion valve 23, to the demethanizer operating pressure, resulting incooling of the total stream to −131° F. [−91° C.]. The expanded stream48 c is then supplied to fractionation tower 18 as the top column feed.The vapor portion of stream 48 c combines with the vapors rising fromthe top fractionation stage of the column to form demethanizer overheadstream 41 at −128° F. [−89° C.].

The liquid product (stream 45) exits the bottom of tower 18 at 70° F.[21° C.], based on a typical specification of a methane to ethane ratioof 0.025:1 on a molar basis in the bottom product. The cold residue gasstream 41 passes countercurrently to the compressed distillation vaporstream in heat exchanger 22 where it is heated to −106° F. [−77° C.](stream 41 a), and countercurrently to the incoming feed gas in heatexchanger 12 where it is heated to −66° F. [−55° C.] (stream 41 b) andin heat exchanger 10 where it is heated to 110° F. [43° C.] (stream 41c). The residue gas is then re-compressed in two stages. The first stageis compressor 16 driven by expansion machine 15. The second stage iscompressor 24 driven by a supplemental power source which compresses theresidue gas (stream 41 e) to sales line pressure. After cooling to 120°F. [49° C.] in discharge cooler 25, the residue gas product (stream 41f) flows to the sales gas pipeline at 1025 psia [7,067 kPa(a)],sufficient to meet line requirements (usually on the order of the inletpressure).

A summary of stream flow rates and energy consumption for the processillustrated in FIG. 1 is set forth in the following table:

TABLE I (FIG. 1) Stream Flow Summary - Lb. Moles/Hr [kg moles/Hr] StreamMethane Ethane Propane Butanes+ Total 31 25,382 1,161 362 332 28,055 3225,050 1,096 311 180 27,431 33 332 65 51 152 624 36 5,636 247 70 406,172 39 19,414 849 241 140 21,259 48 3,962 100 3 0 4,200 41 25,358 1972 0 26,056 45 24 964 360 332 1,999 Recoveries* Ethane 83.06% Propane99.50% Butanes+ 99.98% Power Residue Gas Compression 10,783 HP [17,727kW] Recycle Compression   260 HP   [427 kW] Total Compression 11,043 HP[18,154 kW] *(Based on un-rounded flow rates)

DESCRIPTION OF THE INVENTION

FIG. 2 illustrates a flow diagram of a process in accordance with thepresent invention. The feed gas composition and conditions considered inthe process presented in FIG. 2 are the same as those in FIG. 1.Accordingly, the FIG. 2 process can be compared with that of the FIG. 1process to illustrate the advantages of the present invention.

In the simulation of the FIG. 2 process, inlet gas enters the plant at120° F. [49° C.] and 1025 psia [7,067 kPa(a)] as stream 31 and is cooledin heat exchanger 10 by heat exchange with cool residue gas (stream 46b), demethanizer reboiler liquids at 50° F. [10° C.] (stream 44),demethanizer lower side reboiler liquids at 8° F. [−13° C.] (stream 43),and demethanizer upper side reboiler liquids at −67° F. [−55° C.](stream 42). The cooled stream 31 a enters separator 11 at −38° F. [−39°C.] and 1015 psia [6,998 kPa(a)] where the vapor (stream 32) isseparated from the condensed liquid (stream 33). The separator liquid(stream 33/40) is expanded to the operating pressure (approximately 469psia [3,234 kPa(a)]) of fractionation tower 18 by expansion valve 17,cooling stream 40 a to −67° F. [−55° C.] before it is supplied tofractionation tower 18 at a lower mid-column feed point (located belowthe feed point of stream 39 a described later in paragraph [0031]).

The vapor (stream 32) from separator 11 is divided into two streams, 34and 39. Stream 34, containing about 26% of the total vapor, passesthrough heat exchanger 12 in heat exchange relation with the coldresidue gas (stream 46 a) where it is cooled to substantialcondensation. The resulting substantially condensed stream 36 a at −106°F. [−76° C.] is then divided into two portions, streams 37 and 38.Stream 38, containing about 50.5% of the total substantially condensedstream, is flash expanded through expansion valve 14 to the operatingpressure of fractionation tower 18. During expansion a portion of thestream is vaporized, resulting in cooling of the total stream. In theprocess illustrated in FIG. 2, the expanded stream 38 a leavingexpansion valve 14 reaches a temperature of −127° F. [−88° C.] before itis supplied at an upper mid-column feed point, in absorbing section 18 aof fractionation tower 18. The remaining 49.5% of the substantiallycondensed stream (stream 37) is flash expanded through expansion valve13 to slightly above the operating pressure of fractionation tower 18.The flash expanded stream 37 a is warmed slightly in heat exchanger 22from −126° F. [−88° C.] to −125° F. [−87° C.], and the resulting stream37 b is then supplied at another upper mid-column feed point inabsorbing section 18 a of fractionation tower 18.

The remaining 74% of the vapor from separator 11 (stream 39) enters awork expansion machine 15 in which mechanical energy is extracted fromthis portion of the high pressure feed. The machine 15 expands the vaporsubstantially isentropically to the tower operating pressure, with thework expansion cooling the expanded stream 39 a to a temperature ofapproximately −100° F. [−73° C.]. The partially condensed expandedstream 39 a is thereafter supplied as feed to fractionation tower 18 ata mid-column feed point (located below the feed points of streams 38 aand 37 b).

The demethanizer in tower 18 is a conventional distillation columncontaining a plurality of vertically spaced trays, one or more packedbeds, or some combination of trays and packing. The demethanizer towerconsists of two sections: an upper absorbing (rectification) section 18a that contains the trays and/or packing to provide the necessarycontact between the vapor portion of the expanded streams 38 a and 39 aand heated expanded stream 37 b rising upward and cold liquid fallingdownward to condense and absorb the C₂ components, C₃ components, andheavier components from the vapors rising upward; and a lower, strippingsection 18 b that contains the trays and/or packing to provide thenecessary contact between the liquids falling downward and the vaporsrising upward. The demethanizing section 18 b also includes one or morereboilers (such as the reboiler and side reboilers described previously)which heat and vaporize a portion of the liquids flowing down the columnto provide the stripping vapors which flow up the column to strip theliquid product, stream 45, of methane and lighter components. Stream 39a enters demethanizer 18 at an intermediate feed position located in thelower region of absorbing section 18 a of demethanizer 18. The liquidportion of the expanded stream commingles with liquids falling downwardfrom absorbing section 18 a and the combined liquid continues downwardinto stripping section 18 b of demethanizer 18. The vapor portion of theexpanded stream commingles with vapors arising from stripping section 18b and the combined vapor rises upward through absorbing section 18 a andis contacted with cold liquid falling downward to condense and absorbthe C₂ components, C₃ components, and heavier components.

A portion of the distillation vapor (stream 48) is withdrawn from anintermediate region of absorbing section 18 a in fractionation column18, above the feed position of expanded stream 39 a in the lower regionof absorbing section 18 a and below the feed positions of expandedstream 38 a and heated expanded stream 37 b. The distillation vaporstream 48 at −116° F. [−82° C.] is combined with a portion (stream 47)of overhead vapor stream 41 at −128° F. [−89° C.] to form combined vaporstream 49 at −118° F. [−83° C.]. The combined vapor stream 49 iscompressed to 592 psia [4,080 kPa(a)] (stream 49 a) by reflux compressor21, then cooled from −92° F. [−69° C.] to −124° F. [−87° C.] andsubstantially condensed (stream 49 b) in heat exchanger 22 by heatexchange with residue gas stream 46 (the remaining portion of colddemethanizer overhead stream 41 exiting the top of demethanizer 18) andwith the flash expanded stream 37 a as described previously. The coldresidue gas stream is warmed to −110° F. [−79° C.] (stream 46 a) as itprovides cooling to the compressed combined vapor stream 49 a.

The substantially condensed stream 49 b is flash expanded to theoperating pressure of demethanizer 18 by expansion valve 23. A portionof the stream is vaporized, further cooling stream 49 c to −132° F.[−91° C.] before it is supplied as cold top column feed (reflux) todemethanizer 18. This cold liquid reflux absorbs and condenses the C₂components, C₃ components, and heavier components rising in the upperrectification region of absorbing section 18 a of demethanizer 18.

In stripping section 18 b of demethanizer 18, the feed streams arestripped of their methane and lighter components. The resulting liquidproduct (stream 45) exits the bottom of tower 18 at 68° F. [20° C.](based on a typical specification of a methane to ethane ratio of0.025:1 on a molar basis in the bottom product). The partially warmedresidue gas stream 46 a passes countercurrently to the incoming feed gasin heat exchanger 12 where it is heated to −61° F. [−52° C.] (stream 46b) and in heat exchanger 10 where it is heated to 112° F. [44° C.](stream 46 c) as it provides cooling as previously described. Theresidue gas is then re-compressed in two stages, compressor 16 driven byexpansion machine 15 and compressor 24 driven by a supplemental powersource. After stream 46 e is cooled to 120° F. [49° C.] in dischargecooler 25, the residue gas product (stream 46 f) flows to the sales gaspipeline at 1025 psia [7,067 kPa(a)], sufficient to meet linerequirements (usually on the order of the inlet pressure).

A summary of stream flow rates and energy consumption for the processillustrated in FIG. 2 is set forth in the following table:

TABLE II (FIG. 2) Stream Flow Summary - Lb. Moles/Hr [kg moles/Hr]Stream Methane Ethane Propane Butanes+ Total 31 25,382 1,161 362 33228,055 32 25,050 1,096 310 180 27,431 33 332 65 52 152 624 34 6,563 28781 47 7,187 35 0 0 0 0 0 36 6,563 287 81 47 7,187 37 3,249 142 40 233,558 38 3,314 145 41 24 3,629 39 18,487 809 229 133 20,244 40 332 65 52152 624 41 25,874 178 1 0 26,534 47 517 4 0 0 531 48 3,801 79 2 0 4,00049 4,318 83 2 0 4,531 46 25,357 174 1 0 26,003 45 25 987 361 332 2,052Recoveries* Ethane 84.98% Propane 99.67% Butanes+ 99.99% Power ResidueGas Compression 10,801 HP [17,757 kW] Reflux Compression   241 HP   [396kW] Total Compression 11,042 HP [18,153 kW] *(Based on un-rounded flowrates)

A comparison of Tables I and II shows that, compared to the prior art,the present invention improves ethane recovery from 83.06% to 84.98%,propane recovery from 99.50% to 99.67%, and butanes+recovery from 99.98%to 99.99%. Comparison of Tables I and II further shows that theimprovement in yields was achieved using essentially the same power asthe prior art. In terms of the recovery efficiency (defined by thequantity of ethane recovered per unit of power), the present inventionrepresents a 2% improvement over the prior art of the FIG. 1 process.

The improvement in the recovery efficiency of the present invention overthat of the prior art processes can be understood by examining theimprovement in the rectification that the present invention provides forthe upper region of absorbing section 18 a. Compared to the prior art ofthe FIG. 1 process, the present invention produces a better top refluxstream containing more methane and less C₂+ components. Comparing refluxstream 48 in Table I for the FIG. 1 prior art process with reflux stream49 in Table II for the present invention, it can be seen that thepresent invention provides a reflux stream that is greater in quantity(nearly 8%) with a significantly lower concentration of C₂+ components(1.9% for the present invention versus 2.5% for the FIG. 1 prior artprocess). Further, because the present invention uses a portion ofsubstantially condensed feed stream 36 a (expanded stream 37 a) tosupplement the cooling provided by the residue gas (stream 46), thecompressed reflux stream 49 a can be substantially condensed at lowerpressure, reducing the power required by reflux compressor 21 comparedto the FIG. 1 prior art process even though the reflux flow rate ishigher for the present invention.

Unlike the prior art process of assignee's U.S. Pat. No. 4,889,545, thepresent invention uses only a portion of substantially condensed feedstream 36 a (expanded stream 37 a) to provide cooling to compressedreflux stream 49 a. This allows the rest of substantially condensed feedstream 36 a (expanded stream 38 a) to provide bulk recovery of the C₂components, C₃ components, and heavier hydrocarbon components containedin expanded feed 39 a and the vapors rising from stripping section 18 b.In the present invention, the cold residue gas (stream 46) is used toprovide most of the cooling of compressed reflux stream 49 a, reducingthe heating of stream 37 a compared to the prior art so that theresulting stream 37 b can supplement the bulk recovery provided byexpanded stream 38 a. The supplemental rectification provided by refluxstream 49 c can then reduce the amount of C₂ components, C₃ components,and C₄+ components contained in the inlet feed gas that is lost to theresidue gas.

The present invention also reduces the rectification required fromreflux stream 49 c in absorbing section 18 a compared to the prior artU.S. Pat. No. 4,889,545 process by condensing reflux stream 49 c withless warming of the column feeds (streams 37 b, 38 a, and 39 a) toabsorbing section 18 a. If all of the substantially condensed stream 36a is expanded and warmed to provide condensing as is taught in U.S. Pat.No. 4,889,545, not only is there less cold liquid in the resultingstream available for rectification of the vapors rising in absorbingsection 18 a, there is much more vapor in the upper region of absorbingsection 18 a that must be rectified by the reflux stream. The net resultis that the reflux stream of the prior art U.S. Pat. No. 4,889,545process allows more of the C₂ components to escape to the residue gasstream than the present invention does, reducing its recovery efficiencycompared to the present invention. The key improvements of the presentinvention over the prior art U.S. Pat. No. 4,889,545 process are thatthe cold residue gas stream 46 is used to provide most of the cooling ofcompressed reflux stream 49 a in heat exchanger 22, and that thedistillation vapor stream 48 contains a significant fraction of C₂components not found in the column overhead stream 41, allowingsufficient methane to be condensed for use as reflux without addingsignificant rectification load in absorbing section 18 a due to theexcessive vaporization of stream 36 a that is inherent when it isexpanded and heated as taught in the U.S. Pat. No. 4,889,545 prior artprocess.

OTHER EMBODIMENTS

In accordance with this invention, it is generally advantageous todesign the absorbing (rectification) section of the demethanizer tocontain multiple theoretical separation stages. However, the benefits ofthe present invention can be achieved with as few as two theoreticalstages. For instance, all or a part of the expanded reflux stream(stream 49 c) leaving expansion valve 23, all or a part of the expandedsubstantially condensed stream 38 a from expansion valve 14, and all ora part of the heated expanded stream 37 b leaving heat exchanger 22 canbe combined (such as in the piping joining the expansion valves and heatexchanger to the demethanizer) and if thoroughly intermingled, thevapors and liquids will mix together and separate in accordance with therelative volatilities of the various components of the total combinedstreams. Such commingling of the three streams, combined with contactingat least a portion of expanded stream 39 a, shall be considered for thepurposes of this invention as constituting an absorbing section.

FIGS. 3 through 6 display other embodiments of the present invention.FIGS. 2 through 4 depict fractionation towers constructed in a singlevessel. FIGS. 5 and 6 depict fractionation towers constructed in twovessels, absorber (rectifier) column 18 (a contacting and separatingdevice) and stripper (distillation) column 20. In such cases, theoverhead vapor stream 54 from stripper column 20 flows to the lowersection of absorber column 18 (via stream 55) to be contacted by refluxstream 49 c, expanded substantially condensed stream 38 a, and heatedexpanded stream 37 b. Pump 19 is used to route the liquids (stream 53)from the bottom of absorber column 18 to the top of stripper column 20so that the two towers effectively function as one distillation system.The decision whether to construct the fractionation tower as a singlevessel (such as demethanizer 18 in FIGS. 2 through 4) or multiplevessels will depend on a number of factors such as plant size, thedistance to fabrication facilities, etc.

Some circumstances may favor withdrawing the distillation vapor stream48 in FIGS. 3 and 4 from the upper region of absorbing section 18 a(stream 50) above the feed point of expanded substantially condensedstream 38 a, rather than from the intermediate region of absorbingsection 18 a (stream 51) below the feed point of expanded substantiallycondensed stream 38 a. Likewise in FIGS. 5 and 6, the vapor distillationstream 48 may be withdrawn from absorber column 18 above the feed pointof expanded substantially condensed stream 38 a

-   -   (stream 50) or below the feed point of expanded substantially        condensed stream 38 a (stream 51). In other cases, it may be        advantageous to withdraw the distillation vapor stream 48 from        the upper region of stripping section 18 b in demethanizer 18        (stream 52) in FIGS. 3 and 4. Similarly in FIGS. 5 and 6, a        portion (stream 52) of overhead vapor stream 54 from stripper        column 20 may be combined with stream 47 to form stream 49, with        any remaining portion (stream 55) flowing to the lower section        of absorber column 18.

As described earlier, the compressed combined vapor stream 49 a issubstantially condensed and the resulting condensate used to absorbvaluable C₂ components, C₃ components, and heavier components from thevapors rising through absorbing section 18 a of demethanizer 18 orthrough absorber column 18. However, the present invention is notlimited to this embodiment. It may be advantageous, for instance, totreat only a portion of these vapors in this manner, or to use only aportion of the condensate as an absorbent, in cases where other designconsiderations indicate portions of the vapors or the condensate shouldbypass absorbing section 18 a of demethanizer 18 or absorber column 18.Some circumstances may favor partial condensation, rather thansubstantial condensation, of compressed combined vapor stream 49 a inheat exchanger 22. Other circumstances may favor that distillation vaporstream 48 be a total vapor side draw from fractionation column 18 orabsorber column 18 rather than a partial vapor side draw. It should alsobe noted that, depending on the composition of the feed gas stream, itmay be advantageous to use external refrigeration to provide partialcooling of compressed combined vapor stream 49 a in heat exchanger 22.

Feed gas conditions, plant size, available equipment, or other factorsmay indicate that elimination of work expansion machine 15, orreplacement with an alternate expansion device (such as an expansionvalve), is feasible. Although individual stream expansion is depicted inparticular expansion devices, alternative expansion means may beemployed where appropriate. For example, conditions may warrant workexpansion of the substantially condensed portions of the feed stream(streams 37 and 38) or the substantially condensed reflux stream leavingheat exchanger 22 (stream 49 b).

Depending on the quantity of heavier hydrocarbons in the feed gas andthe feed gas pressure, the cooled feed stream 31 a leaving heatexchanger 10 in FIGS. 2 through 6 may not contain any liquid (because itis above its dewpoint, or because it is above its cricondenbar). In suchcases, separator 11 shown in FIGS. 2 through 6 is not required.

In accordance with the present invention, the splitting of the vaporfeed may be accomplished in several ways. In the processes of FIGS. 2,3, and 5, the splitting of vapor occurs following cooling and separationof any liquids which may have been formed. The high pressure gas may besplit, however, prior to any cooling of the inlet gas as shown in FIGS.4 and 6. In some embodiments, vapor splitting may be effected in aseparator.

The high pressure liquid (stream 33 in FIGS. 2 through 6) need not beexpanded and fed to a mid-column feed point on the distillation column.Instead, all or a portion of it may be combined with the portion of theseparator vapor (stream 34 in FIGS. 2, 3, and 5) or the portion of thecooled feed gas (stream 34 a in FIGS. 4 and 6) flowing to heat exchanger12. (This is shown by the dashed stream 35 in FIGS. 2 through 6.) Anyremaining portion of the liquid may be expanded through an appropriateexpansion device, such as an expansion valve or expansion machine, andfed to a mid-column feed point on the distillation column (stream 40 ain FIGS. 2 through 6). Stream 40 may also be used for inlet gas coolingor other heat exchange service before or after the expansion step priorto flowing to the demethanizer.

In accordance with the present invention, the use of externalrefrigeration to supplement the cooling available to the inlet gas fromother process streams may be employed, particularly in the case of arich inlet gas. The use and distribution of separator liquids anddemethanizer side draw liquids for process heat exchange, and theparticular arrangement of heat exchangers for inlet gas cooling must beevaluated for each particular application, as well as the choice ofprocess streams for specific heat exchange services.

It will also be recognized that the relative amount of feed found ineach branch of the split vapor feed will depend on several factors,including gas pressure, feed gas composition, the amount of heat whichcan economically be extracted from the feed, and the quantity ofhorsepower available. More feed to the top of the column may increaserecovery while decreasing power recovered from the expander therebyincreasing the recompression horsepower requirements. Increasing feedlower in the column reduces the horsepower consumption but may alsoreduce product recovery. The relative locations of the mid-column feedsmay vary depending on inlet composition or other factors such as desiredrecovery levels and amount of liquid formed during inlet gas cooling.Moreover, two or more of the feed streams, or portions thereof, may becombined depending on the relative temperatures and quantities ofindividual streams, and the combined stream then fed to a mid-columnfeed position. For instance, circumstances may favor combining expandedsubstantially condensed stream 38 a with heated expanded stream 37 b andsupplying the combined stream to a single upper mid-column feed point onfractionation tower 18 (FIGS. 2 through 4) or absorber column 18 (FIGS.5 and 6).

The present invention provides improved recovery of C₂ components, C₃components, and heavier hydrocarbon components or of C₃ components andheavier hydrocarbon components per amount of utility consumptionrequired to operate the process. An improvement in utility consumptionrequired for operating the demethanizer or deethanizer process mayappear in the form of reduced power requirements for compression orre-compression, reduced power requirements for external refrigeration,reduced energy requirements for tower reboilers, or a combinationthereof.

While there have been described what are believed to be preferredembodiments of the invention, those skilled in the art will recognizethat other and further modifications may be made thereto, e.g. to adaptthe invention to various conditions, types of feed, or otherrequirements without departing from the spirit of the present inventionas defined by the following claims.

We claim:
 1. In a process for the separation of a gas stream containingmethane, C₂ components, C₃ components, and heavier hydrocarboncomponents into a volatile residue gas fraction and a relatively lessvolatile fraction containing a major portion of said C₂ components, C₃components, and heavier hydrocarbon components or said C₃ components andheavier hydrocarbon components, in which process (a) said gas stream iscooled under pressure to provide a cooled stream; (b) said cooled streamis expanded to a lower pressure whereby it is further cooled; and (c)said further cooled stream is directed into a distillation column andfractionated at said lower pressure whereby the components of saidrelatively less volatile fraction are recovered; the improvement whereinfollowing cooling, said cooled stream is divided into first and secondstreams; and (1) said first stream is cooled to condense substantiallyall of it; (2) said substantially condensed first stream is divided intoat least a first condensed portion and a second condensed portion; (3)said first condensed portion is expanded to said lower pressure wherebyit is further cooled, and is thereafter supplied to said distillationcolumn at an upper mid-column feed position; (4) said second condensedportion is expanded to said lower pressure whereby it is further cooled,is heated, and is thereafter supplied to said distillation column atsaid upper mid-column feed position; (5) said second stream is expandedto said lower pressure and is supplied to said distillation column at amid-column feed position below said upper mid-column feed position; (6)an overhead vapor stream is withdrawn from an upper region of saiddistillation column and divided into at least a first vapor portion anda second vapor portion; (7) said second vapor portion is heated,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (8) a distillation vaporstream is withdrawn from a region of said distillation column below saidupper mid-column feed position and above said mid-column feed positionand is combined with said first vapor portion to form a combined vaporstream; (9) said combined vapor stream is compressed to higher pressure;(10) said compressed combined vapor stream is cooled sufficiently tocondense at least a part of it, thereby forming a condensed stream whilesupplying at least a portion of the heating of steps (4) and (7); (11)at least a portion of said condensed stream is expanded to said lowerpressure and is thereafter supplied to said distillation column at a topfeed position; and (12) the quantities and temperatures of said feedstreams to said distillation column are effective to maintain theoverhead temperature of said distillation column at a temperaturewhereby the major portions of the components in said relatively lessvolatile fraction are recovered.
 2. In a process for the separation of agas stream containing methane, C₂ components, C₃ components, and heavierhydrocarbon components into a volatile residue gas fraction and arelatively less volatile fraction containing a major portion of said C₂components, C₃ components, and heavier hydrocarbon components or said C₃components and heavier hydrocarbon components, in which process (a) saidgas stream is cooled under pressure to provide a cooled stream; (b) saidcooled stream is expanded to a lower pressure whereby it is furthercooled; and (c) said further cooled stream is directed into adistillation column and fractionated at said lower pressure whereby thecomponents of said relatively less volatile fraction are recovered; theimprovement wherein prior to cooling, said gas stream is divided intofirst and second streams; and (1) said first stream is cooled tocondense substantially all of it; (2) said substantially condensed firststream is divided into at least a first condensed portion and a secondcondensed portion; (3) said first condensed portion is expanded to saidlower pressure whereby it is further cooled, and is thereafter suppliedto said distillation column at an upper mid-column feed position; (4)said second condensed portion is expanded to said lower pressure wherebyit is further cooled, is heated, and is thereafter supplied to saiddistillation column at said upper mid-column feed position; (5) saidsecond stream is cooled and thereafter expanded to said lower pressureand supplied to said distillation column at a mid-column feed positionbelow said upper mid-column feed position; (6) an overhead vapor streamis withdrawn from an upper region of said distillation column anddivided into at least a first vapor portion and a second vapor portion;(7) said second vapor portion is heated, thereafter discharging at leasta portion of said heated second vapor portion as said volatile residuegas fraction; (8) a distillation vapor stream is withdrawn from a regionof said distillation column below said upper mid-column feed positionand above said mid-column feed position and is combined with said firstvapor portion to form a combined vapor stream; (9) said combined vaporstream is compressed to higher pressure; (10) said compressed combinedvapor stream is cooled sufficiently to condense at least a part of it,thereby forming a condensed stream while supplying at least a portion ofthe heating of steps (4) and (7); (11) at least a portion of saidcondensed stream is expanded to said lower pressure and is thereaftersupplied to said distillation column at a top feed position; and (12)the quantities and temperatures of said feed streams to saiddistillation column are effective to maintain the overhead temperatureof said distillation column at a temperature whereby the major portionsof the components in said relatively less volatile fraction arerecovered.
 3. In a process for the separation of a gas stream containingmethane, C₂ components, C₃ components, and heavier hydrocarboncomponents into a volatile residue gas fraction and a relatively lessvolatile fraction containing a major portion of said C₂ components, C₃components, and heavier hydrocarbon components or said C₃ components andheavier hydrocarbon components, in which process (a) said gas stream iscooled under pressure to provide a cooled stream; (b) said cooled streamis expanded to a lower pressure whereby it is further cooled; and (c)said further cooled stream is directed into a distillation column andfractionated at said lower pressure whereby the components of saidrelatively less volatile fraction are recovered; the improvement whereinsaid gas stream is cooled sufficiently to partially condense it; and (1)said partially condensed gas stream is separated thereby to provide avapor stream and at least one liquid stream; (2) said vapor stream isthereafter divided into first and second streams; (3) said first streamis cooled to condense substantially all of it; (4) said substantiallycondensed first stream is divided into at least a first condensedportion and a second condensed portion; (5) said first condensed portionis expanded to said lower pressure whereby it is further cooled, and isthereafter supplied to said distillation column at an upper mid-columnfeed position; (6) said second condensed portion is expanded to saidlower pressure whereby it is further cooled, is heated, and isthereafter supplied to said distillation column at said upper mid-columnfeed position; (7) said second stream is expanded to said lower pressureand is supplied to said distillation column at a mid-column feedposition below said upper mid-column feed position; (8) at least aportion of said at least one liquid stream is expanded to said lowerpressure and is supplied to said distillation column at a lowermid-column feed position below said mid-column feed position; (9) anoverhead vapor stream is withdrawn from an upper region of saiddistillation column and divided into at least a first vapor portion anda second vapor portion; (10) said second vapor portion is heated,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (11) a distillation vaporstream is withdrawn from a region of said distillation column below saidupper mid-column feed position and above said mid-column feed positionand is combined with said first vapor portion to form a combined vaporstream; (12) said combined vapor stream is compressed to higherpressure; (13) said compressed combined vapor stream is cooledsufficiently to condense at least a part of it, thereby forming acondensed stream while supplying at least a portion of the heating ofsteps (6) and (10); (14) at least a portion of said condensed stream isexpanded to said lower pressure and is thereafter supplied to saiddistillation column at a top feed position; and (15) the quantities andtemperatures of said feed streams to said distillation column areeffective to maintain the overhead temperature of said distillationcolumn at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 4. In a processfor the separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, inwhich process (a) said gas stream is cooled under pressure to provide acooled stream; (b) said cooled stream is expanded to a lower pressurewhereby it is further cooled; and (c) said further cooled stream isdirected into a distillation column and fractionated at said lowerpressure whereby the components of said relatively less volatilefraction are recovered; the improvement wherein prior to cooling, saidgas stream is divided into first and second streams; and (1) said firststream is cooled to condense substantially all of it; (2) saidsubstantially condensed first stream is divided into at least a firstcondensed portion and a second condensed portion; (3) said firstcondensed portion is expanded to said lower pressure whereby it isfurther cooled, and is thereafter supplied to said distillation columnat an upper mid-column feed position; (4) said second condensed portionis expanded to said lower pressure whereby it is further cooled, isheated, and is thereafter supplied to said distillation column at saidupper mid-column feed position; (5) said second stream is cooled underpressure sufficiently to partially condense it; (6) said partiallycondensed second stream is separated thereby to provide a vapor streamand at least one liquid stream; (7) said vapor stream is expanded tosaid lower pressure and is supplied to said distillation column at amid-column feed position below said upper mid-column feed position; (8)at least a portion of said at least one liquid stream is expanded tosaid lower pressure and is supplied to said distillation column at alower mid-column feed position below said mid-column feed position; (9)an overhead vapor stream is withdrawn from an upper region of saiddistillation column and divided into at least a first vapor portion anda second vapor portion; (10) said second vapor portion is heated,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (11) a distillation vaporstream is withdrawn from a region of said distillation column below saidupper mid-column feed position and above said mid-column feed positionand is combined with said first vapor portion to form a combined vaporstream; (12) said combined vapor stream is compressed to higherpressure; (13) said compressed combined vapor stream is cooledsufficiently to condense at least a part of it, thereby forming acondensed stream while supplying at least a portion of the heating ofsteps (4) and (10); (14) at least a portion of said condensed stream isexpanded to said lower pressure and is thereafter supplied to saiddistillation column at a top feed position; and (15) the quantities andtemperatures of said feed streams to said distillation column areeffective to maintain the overhead temperature of said distillationcolumn at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 5. In a processfor the separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, inwhich process (a) said gas stream is cooled under pressure to provide acooled stream; (b) said cooled stream is expanded to a lower pressurewhereby it is further cooled; and (c) said further cooled stream isdirected into a distillation column and fractionated at said lowerpressure whereby the components of said relatively less volatilefraction are recovered; the improvement wherein said gas stream iscooled sufficiently to partially condense it; and (1) said partiallycondensed gas stream is separated thereby to provide a vapor stream andat least one liquid stream; (2) said vapor stream is thereafter dividedinto first and second streams; (3) said first stream is combined with atleast a portion of said at least one liquid stream to form a combinedstream, whereupon said combined stream is cooled to condensesubstantially all of it; (4) said substantially condensed combinedstream is divided into at least a first condensed portion and a secondcondensed portion; (5) said first condensed portion is expanded to saidlower pressure whereby it is further cooled, and is thereafter suppliedto said distillation column at an upper mid-column feed position; (6)said second condensed portion is expanded to said lower pressure wherebyit is further cooled, is heated, and is thereafter supplied to saiddistillation column at said upper mid-column feed position; (7) saidsecond stream is expanded to said lower pressure and is supplied to saiddistillation column at a mid-column feed position below said uppermid-column feed position; (8) any remaining portion of said at least oneliquid stream is expanded to said lower pressure and is supplied to saiddistillation column at a lower mid-column feed position below saidmid-column feed position; (9) an overhead vapor stream is withdrawn froman upper region of said distillation column and divided into at least afirst vapor portion and a second vapor portion; (10) said second vaporportion is heated, thereafter discharging at least a portion of saidheated second vapor portion as said volatile residue gas fraction; (11)a distillation vapor stream is withdrawn from a region of saiddistillation column below said upper mid-column feed position and abovesaid mid-column feed position and is combined with said first vaporportion to form a combined vapor stream; (12) said combined vapor streamis compressed to higher pressure; (13) said compressed combined vaporstream is cooled sufficiently to condense at least a part of it, therebyforming a condensed stream while supplying at least a portion of theheating of steps (6) and (10); (14) at least a portion of said condensedstream is expanded to said lower pressure and is thereafter supplied tosaid distillation column at a top feed position; and (15) the quantitiesand temperatures of said feed streams to said distillation column areeffective to maintain the overhead temperature of said distillationcolumn at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 6. In a processfor the separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, inwhich process (a) said gas stream is cooled under pressure to provide acooled stream; (b) said cooled stream is expanded to a lower pressurewhereby it is further cooled; and (c) said further cooled stream isdirected into a distillation column and fractionated at said lowerpressure whereby the components of said relatively less volatilefraction are recovered; the improvement wherein following cooling, saidcooled stream is divided into first and second streams; and (1) saidfirst stream is cooled to condense substantially all of it; (2) saidsubstantially condensed first stream is divided into at least a firstcondensed portion and a second condensed portion; (3) said firstcondensed portion is expanded to said lower pressure whereby it isfurther cooled, and is thereafter supplied at a mid-column feed positionto a contacting and separating device that produces a first overheadvapor stream and a bottom liquid stream, whereupon said bottom liquidstream is supplied to said distillation column; (4) said secondcondensed portion is expanded to said lower pressure whereby it isfurther cooled, is heated, and is thereafter supplied to said contactingand separating device at said mid-column feed position; (5) said secondstream is expanded to said lower pressure and is supplied to saidcontacting and separating device at a first lower column feed positionbelow said mid-column feed position; (6) a second overhead vapor streamis withdrawn from an upper region of said distillation column and issupplied to said contacting and separating device at a second lowercolumn feed position below said mid-column feed position; (7) said firstoverhead vapor stream is divided into at least a first vapor portion anda second vapor portion; (8) said second vapor portion is heated,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (9) a distillation vaporstream is withdrawn from a region of said contacting and separatingdevice below said mid-column feed position and above said first andsecond lower column feed positions and is combined with said first vaporportion to form a combined vapor stream; (10) said combined vapor streamis compressed to higher pressure; (11) said compressed combined vaporstream is cooled sufficiently to condense at least a part of it, therebyforming a condensed stream while supplying at least a portion of theheating of steps (4) and (8); (12) at least a portion of said condensedstream is expanded to said lower pressure and is thereafter supplied tosaid contacting and separating device at a top feed position; and (13)the quantities and temperatures of said feed streams to said contactingand separating device are effective to maintain the overhead temperatureof said contacting and separating device at a temperature whereby themajor portions of the components in said relatively less volatilefraction are recovered.
 7. In a process for the separation of a gasstream containing methane, C₂ components, C₃ components, and heavierhydrocarbon components into a volatile residue gas fraction and arelatively less volatile fraction containing a major portion of said C₂components, C₃ components, and heavier hydrocarbon components or said C₃components and heavier hydrocarbon components, in which process (a) saidgas stream is cooled under pressure to provide a cooled stream; (b) saidcooled stream is expanded to a lower pressure whereby it is furthercooled; and (c) said further cooled stream is directed into adistillation column and fractionated at said lower pressure whereby thecomponents of said relatively less volatile fraction are recovered; theimprovement wherein prior to cooling, said gas stream is divided intofirst and second streams; and (1) said first stream is cooled tocondense substantially all of it; (2) said substantially condensed firststream is divided into at least a first condensed portion and a secondcondensed portion; (3) said first condensed portion is expanded to saidlower pressure whereby it is further cooled, and is thereafter suppliedat a mid-column feed position to a contacting and separating device thatproduces a first overhead vapor stream and a bottom liquid stream,whereupon said bottom liquid stream is supplied to said distillationcolumn; (4) said second condensed portion is expanded to said lowerpressure whereby it is further cooled, is heated, and is thereaftersupplied to said contacting and separating device at said mid-columnfeed position; (5) said second stream is cooled and thereafter expandedto said lower pressure and supplied to said contacting and separatingdevice at a first lower column feed position below said mid-column feedposition; (6) a second overhead vapor stream is withdrawn from an upperregion of said distillation column and is supplied to said contactingand separating device at a second lower column feed position below saidmid-column feed position; (7) said first overhead vapor stream isdivided into at least a first vapor portion and a second vapor portion;(8) said second vapor portion is heated, thereafter discharging at leasta portion of said heated second vapor portion as said volatile residuegas fraction; (9) a distillation vapor stream is withdrawn from a regionof said contacting and separating device below said mid-column feedposition and above said first and second lower column feed positions andis combined with said first vapor portion to form a combined vaporstream; (10) said combined vapor stream is compressed to higherpressure; (11) said compressed combined vapor stream is cooledsufficiently to condense at least a part of it, thereby forming acondensed stream while supplying at least a portion of the heating ofsteps (4) and (8); (12) at least a portion of said condensed stream isexpanded to said lower pressure and is thereafter supplied to saidcontacting and separating device at a top feed position; and (13) thequantities and temperatures of said feed streams to said contacting andseparating device are effective to maintain the overhead temperature ofsaid contacting and separating device at a temperature whereby the majorportions of the components in said relatively less volatile fraction arerecovered.
 8. In a process for the separation of a gas stream containingmethane, C₂ components, C₃ components, and heavier hydrocarboncomponents into a volatile residue gas fraction and a relatively lessvolatile fraction containing a major portion of said C₂ components, C₃components, and heavier hydrocarbon components or said C₃ components andheavier hydrocarbon components, in which process (a) said gas stream iscooled under pressure to provide a cooled stream; (b) said cooled streamis expanded to a lower pressure whereby it is further cooled; and (c)said further cooled stream is directed into a distillation column andfractionated at said lower pressure whereby the components of saidrelatively less volatile fraction are recovered; the improvement whereinsaid gas stream is cooled sufficiently to partially condense it; and (1)said partially condensed gas stream is separated thereby to provide avapor stream and at least one liquid stream; (2) said vapor stream isthereafter divided into first and second streams; (3) said first streamis cooled to condense substantially all of it; (4) said substantiallycondensed first stream is divided into at least a first condensedportion and a second condensed portion; (5) said first condensed portionis expanded to said lower pressure whereby it is further cooled, and isthereafter supplied at a mid-column feed position to a contacting andseparating device that produces a first overhead vapor stream and abottom liquid stream, whereupon said bottom liquid stream is supplied tosaid distillation column; (6) said second condensed portion is expandedto said lower pressure whereby it is further cooled, is heated, and isthereafter supplied to said contacting and separating device at saidmid-column feed position; (7) said second stream is expanded to saidlower pressure and is supplied to said contacting and separating deviceat a first lower column feed position below said mid-column feedposition; (8) at least a portion of said at least one liquid stream isexpanded to said lower pressure and is supplied to said distillationcolumn at a mid-column feed position; (9) a second overhead vapor streamis withdrawn from an upper region of said distillation column and issupplied to said contacting and separating device at a second lowercolumn feed position below said mid-column feed position; (10) saidfirst overhead vapor stream is divided into at least a first vaporportion and a second vapor portion; (11) said second vapor portion isheated, thereafter discharging at least a portion of said heated secondvapor portion as said volatile residue gas fraction; (12) a distillationvapor stream is withdrawn from a region of said contacting andseparating device below said mid-column feed position and above saidfirst and second lower column feed positions and is combined with saidfirst vapor portion to form a combined vapor stream; (13) said combinedvapor stream is compressed to higher pressure; (14) said compressedcombined vapor stream is cooled sufficiently to condense at least a partof it, thereby forming a condensed stream while supplying at least aportion of the heating of steps (6) and (11); (15) at least a portion ofsaid condensed stream is expanded to said lower pressure and isthereafter supplied to said contacting and separating device at a topfeed position; and (16) the quantities and temperatures of said feedstreams to said contacting and separating device are effective tomaintain the overhead temperature of said contacting and separatingdevice at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 9. In a processfor the separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, inwhich process (a) said gas stream is cooled under pressure to provide acooled stream; (b) said cooled stream is expanded to a lower pressurewhereby it is further cooled; and (c) said further cooled stream isdirected into a distillation column and fractionated at said lowerpressure whereby the components of said relatively less volatilefraction are recovered; the improvement wherein prior to cooling, saidgas stream is divided into first and second streams; and (1) said firststream is cooled to condense substantially all of it; (2) saidsubstantially condensed first stream is divided into at least a firstcondensed portion and a second condensed portion; (3) said firstcondensed portion is expanded to said lower pressure whereby it isfurther cooled, and is thereafter supplied at a mid-column feed positionto a contacting and separating device that produces a first overheadvapor stream and a bottom liquid stream, whereupon said bottom liquidstream is supplied to said distillation column; (4) said secondcondensed portion is expanded to said lower pressure whereby it isfurther cooled, is heated, and is thereafter supplied to said contactingand separating device at said mid-column feed position; (5) said secondstream is cooled under pressure sufficiently to partially condense it;(6) said partially condensed second stream is separated thereby toprovide a vapor stream and at least one liquid stream; (7) said vaporstream is expanded to said lower pressure and is supplied to saidcontacting and separating device at a first lower column feed positionbelow said mid-column feed position; (8) at least a portion of said atleast one liquid stream is expanded to said lower pressure and issupplied to said distillation column at a mid-column feed position; (9)a second overhead vapor stream is withdrawn from an upper region of saiddistillation column and is supplied to said contacting and separatingdevice at a second lower column feed position below said mid-column feedposition; (10) said first overhead vapor stream is divided into at leasta first vapor portion and a second vapor portion; (11) said second vaporportion is heated, thereafter discharging at least a portion of saidheated second vapor portion as said volatile residue gas fraction; (12)a distillation vapor stream is withdrawn from a region of saidcontacting and separating device below said mid-column feed position andabove said first and second lower column feed positions and is combinedwith said first vapor portion to form a combined vapor stream; (13) saidcombined vapor stream is compressed to higher pressure; (14) saidcompressed combined vapor stream is cooled sufficiently to condense atleast a part of it, thereby forming a condensed stream while supplyingat least a portion of the heating of steps (4) and (11); (15) at least aportion of said condensed stream is expanded to said lower pressure andis thereafter supplied to said contacting and separating device at a topfeed position; and (16) the quantities and temperatures of said feedstreams to said contacting and separating device are effective tomaintain the overhead temperature of said contacting and separatingdevice at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 10. In a processfor the separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, inwhich process (a) said gas stream is cooled under pressure to provide acooled stream; (b) said cooled stream is expanded to a lower pressurewhereby it is further cooled; and (c) said further cooled stream isdirected into a distillation column and fractionated at said lowerpressure whereby the components of said relatively less volatilefraction are recovered; the improvement wherein said gas stream iscooled sufficiently to partially condense it; and (1) said partiallycondensed gas stream is separated thereby to provide a vapor stream andat least one liquid stream; (2) said vapor stream is thereafter dividedinto first and second streams; (3) said first stream is combined with atleast a portion of said at least one liquid stream to form a combinedstream, whereupon said combined stream is cooled to condensesubstantially all of it; (4) said substantially condensed combinedstream is divided into at least a first condensed portion and a secondcondensed portion; (5) said first condensed portion is expanded to saidlower pressure whereby it is further cooled, and is thereafter suppliedat a mid-column feed position to a contacting and separating device thatproduces a first overhead vapor stream and a bottom liquid stream,whereupon said bottom liquid stream is supplied to said distillationcolumn; (6) said second condensed portion is expanded to said lowerpressure whereby it is further cooled, is heated, and is thereaftersupplied to said contacting and separating device at said mid-columnfeed position; (7) said second stream is expanded to said lower pressureand is supplied to said contacting and separating device at a firstlower column feed position below said mid-column feed position; (8) anyremaining portion of said at least one liquid stream is expanded to saidlower pressure and is supplied to said distillation column at amid-column feed position; (9) a second overhead vapor stream iswithdrawn from an upper region of said distillation column and issupplied to said contacting and separating device at a second lowercolumn feed position below said mid-column feed position; (10) saidfirst overhead vapor stream is divided into at least a first vaporportion and a second vapor portion; (11) said second vapor portion isheated, thereafter discharging at least a portion of said heated secondvapor portion as said volatile residue gas fraction; (12) a distillationvapor stream is withdrawn from a region of said contacting andseparating device below said mid-column feed position and above saidfirst and second lower column feed positions and is combined with saidfirst vapor portion to form a combined vapor stream; (13) said combinedvapor stream is compressed to higher pressure; (14) said compressedcombined vapor stream is cooled sufficiently to condense at least a partof it, thereby forming a condensed stream while supplying at least aportion of the heating of steps (6) and (11); (15) at least a portion ofsaid condensed stream is expanded to said lower pressure and isthereafter supplied to said contacting and separating device at a topfeed position; and (16) the quantities and temperatures of said feedstreams to said contacting and separating device are effective tomaintain the overhead temperature of said contacting and separatingdevice at a temperature whereby the major portions of the components insaid relatively less volatile fraction are recovered.
 11. Theimprovement according to claim 1, 2, 3, 4, or 5 wherein saiddistillation vapor stream is withdrawn from a region of saiddistillation column below said top feed position and above said uppermid-column feed position.
 12. The improvement according to claim 1, 2,3, 4, or 5 wherein said distillation vapor stream is withdrawn from aregion of said distillation column below said mid-column feed position.13. The improvement according to claim 6, 7, 8, 9, or 10 wherein saiddistillation vapor stream is withdrawn from a region of said contactingand separating device below said top feed position and above saidmid-column feed position.
 14. The improvement according to claim 6, 7,8, 9, or 10 wherein said second overhead vapor stream is divided intosaid distillation vapor stream and a second distillation vapor stream,whereupon said second distillation vapor stream is supplied to saidcontacting and separating device at said second lower column feedposition.
 15. The improvement according to claim 1, 2, 3, 4, or 5wherein said heated expanded second condensed portion is supplied tosaid distillation column at a second upper mid-column feed position. 16.The improvement according to claim 11 wherein said heated expandedsecond condensed portion is supplied to said distillation column at asecond upper mid-column feed position.
 17. The improvement according toclaim 12 wherein said heated expanded second condensed portion issupplied to said distillation column at a second upper mid-column feedposition.
 18. The improvement according to claim 6, 7, 8, 9, or 10wherein said heated expanded second condensed portion is supplied tosaid contacting and separating device at a second mid-column feedposition.
 19. The improvement according to claim 13 wherein said heatedexpanded second condensed portion is supplied to said contacting andseparating device at a second mid-column feed position.
 20. Theimprovement according to claim 14 wherein said heated expanded secondcondensed portion is supplied to said contacting and separating deviceat a second mid-column feed position.
 21. In an apparatus for theseparation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, insaid apparatus there being (a) a first cooling means to cool said gasstream under pressure connected to provide a cooled stream underpressure; (b) a first expansion means connected to receive at least aportion of said cooled stream under pressure and expand it to a lowerpressure, whereby said stream is further cooled; and (c) a distillationcolumn connected to receive said further cooled stream, saiddistillation column being adapted to separate said further cooled streaminto an overhead vapor stream and said relatively less volatilefraction; the improvement wherein said apparatus includes (1) firstdividing means connected to said first cooling means to receive saidcooled stream and divide it into first and second streams; (2) secondcooling means connected to said first dividing means to receive saidfirst stream and cool it sufficiently to substantially condense it; (3)second dividing means connected to said second cooling means to receivesaid substantially condensed first stream and divide it into at least afirst condensed portion and a second condensed portion; (4) secondexpansion means connected to said second dividing means to receive saidfirst condensed portion and expand it to said lower pressure, saidsecond expansion means being further connected to said distillationcolumn to supply said expanded first condensed portion to saiddistillation column at an upper mid-column feed position; (5) thirdexpansion means connected to said second dividing means to receive saidsecond condensed portion and expand it to said lower pressure; (6) heatexchange means connected to said third expansion means to receive saidexpanded second condensed portion and heat it, said heat exchange meansbeing further connected to said distillation column to supply saidheated expanded second condensed portion to said distillation column atsaid upper mid-column feed position; (7) said first expansion meansbeing connected to said first dividing means to receive said secondstream and expand it to said lower pressure, said first expansion meansbeing further connected to said distillation column to supply saidexpanded second stream to said distillation column at a mid-column feedposition below said upper mid-column feed position; (8) third dividingmeans connected to said distillation column to receive said overheadvapor stream separated therein and divide it into at least a first vaporportion and a second vapor portion; (9) said heat exchange means beingfurther connected to said third dividing means to receive at least aportion of said second vapor portion and heat it, thereafter dischargingat least a portion of said heated second vapor portion as said volatileresidue gas fraction; (10) vapor withdrawing means connected to saiddistillation column to receive a distillation vapor stream from a regionof said distillation column below said upper mid-column feed positionand above said mid-column feed position; (11) combining means connectedto said third dividing means and said vapor withdrawing means to receivesaid first vapor portion and said distillation vapor stream and form acombined vapor stream; (12) compressing means connected to saidcombining means to receive said combined vapor stream and compress it tohigher pressure; (13) said heat exchange means being further connectedto said compressing means to receive said compressed combined vaporstream and cool it sufficiently to condense at least a part of it,thereby forming a condensed stream while supplying at least a portion ofthe heating of steps (6) and (9); (14) fourth expansion means connectedto said heat exchange means to receive said condensed stream and expandit to said lower pressure, said fourth expansion means being furtherconnected to said distillation column to supply at least a portion ofsaid expanded condensed stream to said distillation column at a top feedposition; and (15) control means adapted to regulate the quantities andtemperatures of said feed streams to said distillation column tomaintain the overhead temperature of said distillation column at atemperature whereby the major portions of the components in saidrelatively less volatile fraction are recovered.
 22. In an apparatus forthe separation of a gas stream containing methane, C₂ components, C₃components, and heavier hydrocarbon components into a volatile residuegas fraction and a relatively less volatile fraction containing a majorportion of said C₂ components, C₃ components, and heavier hydrocarboncomponents or said C₃ components and heavier hydrocarbon components, insaid apparatus there being (a) a first cooling means to cool said gasstream under pressure connected to provide a cooled stream underpressure; (b) a first expansion means connected to receive at least aportion of said cooled stream under pressure and expand it to a lowerpressure, whereby said stream is further cooled; and (c) a distillationcolumn connected to receive said further cooled stream, saiddistillation column being adapted to separate said further cooled streaminto an overhead vapor stream and said relatively less volatilefraction; the improvement wherein said apparatus includes (1) firstdividing means prior to said first cooling means to divide said gasstream into first and second streams; (2) second cooling means connectedto said first dividing means to receive said first stream and cool itsufficiently to substantially condense it; (3) second dividing meansconnected to said second cooling means to receive said substantiallycondensed first stream and divide it into at least a first condensedportion and a second condensed portion; (4) second expansion meansconnected to said second dividing means to receive said first condensedportion and expand it to said lower pressure, said second expansionmeans being further connected to said distillation column to supply saidexpanded first condensed portion to said distillation column at an uppermid-column feed position; (5) third expansion means connected to saidsecond dividing means to receive said second condensed portion andexpand it to said lower pressure; (6) heat exchange means connected tosaid third expansion means to receive said expanded second condensedportion and heat it, said heat exchange means being further connected tosaid distillation column to supply said heated expanded second condensedportion to said distillation column at said upper mid-column feedposition; (7) said first cooling means being connected to said firstdividing means to receive said second stream and cool it; (8) said firstexpansion means being connected to said first cooling means to receivesaid cooled second stream and expand it to said lower pressure, saidfirst expansion means being further connected to said distillationcolumn to supply said expanded cooled second stream to said distillationcolumn at a mid-column feed position below said upper mid-column feedposition; (9) third dividing means connected to said distillation columnto receive said overhead vapor stream separated therein and divide itinto at least a first vapor portion and a second vapor portion; (10)said heat exchange means being further connected to said third dividingmeans to receive at least a portion of said second vapor portion andheat it, thereafter discharging at least a portion of said heated secondvapor portion as said volatile residue gas fraction; (11) vaporwithdrawing means connected to said distillation column to receive adistillation vapor stream from a region of said distillation columnbelow said upper mid-column feed position and above said mid-column feedposition; (12) combining means connected to said third dividing meansand said vapor withdrawing means to receive said first vapor portion andsaid distillation vapor stream and form a combined vapor stream; (13)compressing means connected to said combining means to receive saidcombined vapor stream and compress it to higher pressure; (14) said heatexchange means being further connected to said compressing means toreceive said compressed combined vapor stream and cool it sufficientlyto condense at least a part of it, thereby forming a condensed streamwhile supplying at least a portion of the heating of steps (6) and (10);(15) fourth expansion means connected to said heat exchange means toreceive said condensed stream and expand it to said lower pressure, saidfourth expansion means being further connected to said distillationcolumn to supply at least a portion of said expanded condensed stream tosaid distillation column at a top feed position; and (16) control meansadapted to regulate the quantities and temperatures of said feed streamsto said distillation column to maintain the overhead temperature of saiddistillation column at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 23.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into an overhead vapor stream andsaid relatively less volatile fraction; the improvement wherein saidapparatus includes (1) said first cooling means being adapted to coolsaid gas stream under pressure sufficiently to partially condense it;(2) separating means connected to said first cooling means to receivesaid partially condensed gas stream and separate it into a vapor streamand at least one liquid stream; (3) first dividing means connected tosaid separating means to receive said vapor stream and divide it intofirst and second streams; (4) second cooling means connected to saidfirst dividing means to receive said first stream and cool itsufficiently to substantially condense it; (5) second dividing meansconnected to said second cooling means to receive said substantiallycondensed first stream and divide it into at least a first condensedportion and a second condensed portion; (6) second expansion meansconnected to said second dividing means to receive said first condensedportion and expand it to said lower pressure, said second expansionmeans being further connected to said distillation column to supply saidexpanded first condensed portion to said distillation column at an uppermid-column feed position; (7) third expansion means connected to saidsecond dividing means to receive said second condensed portion andexpand it to said lower pressure; (8) heat exchange means connected tosaid third expansion means to receive said expanded second condensedportion and heat it, said heat exchange means being further connected tosaid distillation column to supply said heated expanded second condensedportion to said distillation column at said upper mid-column feedposition; (9) said first expansion means being connected to said firstdividing means to receive said second stream and expand it to said lowerpressure, said first expansion means being further connected to saiddistillation column to supply said expanded second stream to saiddistillation column at a mid-column feed position below said uppermid-column feed position; (10) fourth expansion means connected to saidseparating means to receive at least a portion of said at least oneliquid stream and expand it to said lower pressure, said fourthexpansion means being further connected to said distillation column tosupply said expanded liquid stream to said distillation column at alower mid-column feed position below said mid-column feed position; (11)third dividing means connected to said distillation column to receivesaid overhead vapor stream separated therein and divide it into at leasta first vapor portion and a second vapor portion; (12) said heatexchange means being further connected to said third dividing means toreceive at least a portion of said second vapor portion and heat it,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (13) vapor withdrawingmeans connected to said distillation column to receive a distillationvapor stream from a region of said distillation column below said uppermid-column feed position and above said mid-column feed position; (14)combining means connected to said third dividing means and said vaporwithdrawing means to receive said first vapor portion and saiddistillation vapor stream and form a combined vapor stream; (15)compressing means connected to said combining means to receive saidcombined vapor stream and compress it to higher pressure; (16) said heatexchange means being further connected to said compressing means toreceive said compressed combined vapor stream and cool it sufficientlyto condense at least a part of it, thereby forming a condensed streamwhile supplying at least a portion of the heating of steps (8) and (12);(17) fifth expansion means connected to said heat exchange means toreceive said condensed stream and expand it to said lower pressure, saidfifth expansion means being further connected to said distillationcolumn to supply at least a portion of said expanded condensed stream tosaid distillation column at a top feed position; and (18) control meansadapted to regulate the quantities and temperatures of said feed streamsto said distillation column to maintain the overhead temperature of saiddistillation column at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 24.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into an overhead vapor stream andsaid relatively less volatile fraction; the improvement wherein saidapparatus includes (1) first dividing means prior to said first coolingmeans to divide said gas stream into first and second streams; (2)second cooling means connected to said first dividing means to receivesaid first stream and cool it sufficiently to substantially condense it;(3) second dividing means connected to said second cooling means toreceive said substantially condensed first stream and divide it into atleast a first condensed portion and a second condensed portion; (4)second expansion means connected to said second dividing means toreceive said first condensed portion and expand it to said lowerpressure, said second expansion means being further connected to saiddistillation column to supply said expanded first condensed portion tosaid distillation column at an upper mid-column feed position; (5) thirdexpansion means connected to said second dividing means to receive saidsecond condensed portion and expand it to said lower pressure; (6) heatexchange means connected to said third expansion means to receive saidexpanded second condensed portion and heat it, said heat exchange meansbeing further connected to said distillation column to supply saidheated expanded second condensed portion to said distillation column atsaid upper mid-column feed position; (7) said first cooling means beingconnected to said first dividing means to receive said second stream,said first cooling means being adapted to cool said second stream underpressure sufficiently to partially condense it; (8) separating meansconnected to said first cooling means to receive said partiallycondensed second stream and separate it into a vapor stream and at leastone liquid stream; (9) said first expansion means being connected tosaid separating means to receive said vapor stream and expand it to saidlower pressure, said first expansion means being further connected tosaid distillation column to supply said expanded vapor stream to saiddistillation column at a mid-column feed position below said uppermid-column feed position; (10) fourth expansion means connected to saidseparating means to receive at least a portion of said at least oneliquid stream and expand it to said lower pressure, said fourthexpansion means being further connected to said distillation column tosupply said expanded liquid stream to said distillation column at alower mid-column feed position below said mid-column feed position; (11)third dividing means connected to said distillation column to receivesaid overhead vapor stream separated therein and divide it into at leasta first vapor portion and a second vapor portion; (12) said heatexchange means being further connected to said third dividing means toreceive at least a portion of said second vapor portion and heat it,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (13) vapor withdrawingmeans connected to said distillation column to receive a distillationvapor stream from a region of said distillation column below said uppermid-column feed position and above said mid-column feed position; (14)combining means connected to said third dividing means and said vaporwithdrawing means to receive said first vapor portion and saiddistillation vapor stream and form a combined vapor stream; (15)compressing means connected to said combining means to receive saidcombined vapor stream and compress it to higher pressure; (16) said heatexchange means being further connected to said compressing means toreceive said compressed combined vapor stream and cool it sufficientlyto condense at least a part of it, thereby forming a condensed streamwhile supplying at least a portion of the heating of steps (6) and (12);(17) fifth expansion means connected to said heat exchange means toreceive said condensed stream and expand it to said lower pressure, saidfifth expansion means being further connected to said distillationcolumn to supply at least a portion of said expanded condensed stream tosaid distillation column at a top feed position; and (18) control meansadapted to regulate the quantities and temperatures of said feed streamsto said distillation column to maintain the overhead temperature of saiddistillation column at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 25.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into an overhead vapor stream andsaid relatively less volatile fraction; the improvement wherein saidapparatus includes (1) said first cooling means being adapted to coolsaid gas stream under pressure sufficiently to partially condense it;(2) separating means connected to said first cooling means to receivesaid partially condensed gas stream and separate it into a vapor streamand at least one liquid stream; (3) first dividing means connected tosaid separating means to receive said vapor stream and divide it intofirst and second streams; (4) first combining means connected to saidfirst dividing means and said separating means to receive said firststream and at least a portion of said at least one liquid stream andform a combined stream; (5) second cooling means connected to said firstcombining means to receive said combined stream and cool it sufficientlyto substantially condense it; (6) second dividing means connected tosaid second cooling means to receive said substantially condensedcombined stream and divide it into at least a first condensed portionand a second condensed portion; (7) second expansion means connected tosaid second dividing means to receive said first condensed portion andexpand it to said lower pressure, said second expansion means beingfurther connected to said distillation column to supply said expandedfirst condensed portion to said distillation column at an uppermid-column feed position; (8) third expansion means connected to saidsecond dividing means to receive said second condensed portion andexpand it to said lower pressure; (9) heat exchange means connected tosaid third expansion means to receive said expanded second condensedportion and heat it, said heat exchange means being further connected tosaid distillation column to supply said heated expanded second condensedportion to said distillation column at said upper mid-column feedposition; (10) said first expansion means being connected to said firstdividing means to receive said second stream and expand it to said lowerpressure, said first expansion means being further connected to saiddistillation column to supply said expanded second stream to saiddistillation column at a mid-column feed position below said uppermid-column feed position; (11) fourth expansion means being connected tosaid separating means to receive any remaining portion of said at leastone liquid stream and expand it to said lower pressure, said fourthexpansion means being further connected to said distillation column tosupply said expanded liquid stream to said distillation column at alower mid-column feed position below said mid-column feed position; (12)third dividing means connected to said distillation column to receivesaid overhead vapor stream separated therein and divide it into at leasta first vapor portion and a second vapor portion; (13) said heatexchange means being further connected to said third dividing means toreceive at least a portion of said second vapor portion and heat it,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (14) vapor withdrawingmeans connected to said distillation column to receive a distillationvapor stream from a region of said distillation column below said uppermid-column feed position and above said mid-column feed position; (15)second combining means connected to said third dividing means and saidvapor withdrawing means to receive said first vapor portion and saiddistillation vapor stream and form a combined vapor stream; (16)compressing means connected to said second combining means to receivesaid combined vapor stream and compress it to higher pressure; (17) saidheat exchange means being further connected to said compressing means toreceive said compressed combined vapor stream and cool it sufficientlyto condense at least a part of it, thereby forming a condensed streamwhile supplying at least a portion of the heating of steps (9) and (13);(18) fifth expansion means connected to said heat exchange means toreceive said condensed stream and expand it to said lower pressure, saidfifth expansion means being further connected to said distillationcolumn to supply at least a portion of said expanded condensed stream tosaid distillation column at a top feed position; and (19) control meansadapted to regulate the quantities and temperatures of said feed streamsto said distillation column to maintain the overhead temperature of saiddistillation column at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 26.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into a first overhead vapor streamand said relatively less volatile fraction; the improvement wherein saidapparatus includes (1) first dividing means connected to said firstcooling means to receive said cooled stream and divide it into first andsecond streams; (2) second cooling means connected to said firstdividing means to receive said first stream and cool it sufficiently tosubstantially condense it; (3) second dividing means connected to saidsecond cooling means to receive said substantially condensed firststream and divide it into at least a first condensed portion and asecond condensed portion; (4) second expansion means connected to saidsecond dividing means to receive said first condensed portion and expandit to said lower pressure, said second expansion means being furtherconnected to a contacting and separating means to supply said expandedfirst condensed portion to said contacting and separating means at amid-column feed position, said contacting and separating means beingadapted to produce a second overhead vapor stream and a bottom liquidstream; (5) third expansion means connected to said second dividingmeans to receive said second condensed portion and expand it to saidlower pressure; (6) heat exchange means connected to said thirdexpansion means to receive said expanded second condensed portion andheat it, said heat exchange means being further connected to saidcontacting and separating means to supply said heated expanded secondcondensed portion to said contacting and separating means at saidmid-column feed position; (7) said first expansion means being connectedto said first dividing means to receive said second stream and expand itto said lower pressure, said first expansion means being furtherconnected to said contacting and separating means to supply saidexpanded second stream to said contacting and separating means at afirst lower column feed position below said mid-column feed position;(8) said distillation column being connected to said contacting andseparating means to receive at least a portion of said bottom liquidstream; (9) said contacting and separating means being further connectedto said distillation column to receive at least a portion of said firstoverhead vapor stream at a second lower column feed position below saidmid-column feed position; (10) third dividing means connected to saidcontacting and separating means to receive said second overhead vaporstream separated therein and divide it into at least a first vaporportion and a second vapor portion; (11) said heat exchange means beingfurther connected to said third dividing means to receive at least aportion of said second vapor portion and heat it, thereafter dischargingat least a portion of said heated second vapor portion as said volatileresidue gas fraction; (12) vapor withdrawing means connected to saidcontacting and separating means to receive a distillation vapor streamfrom a region of said contacting and separating device below saidmid-column feed position and above said first and second lower columnfeed positions; (13) combining means connected to said third dividingmeans and said vapor withdrawing means to receive said first vaporportion and said distillation vapor stream and form a combined vaporstream; (14) compressing means connected to said combining means toreceive said combined vapor stream and compress it to higher pressure;(15) said heat exchange means being further connected to saidcompressing means to receive said compressed combined vapor stream andcool it sufficiently to condense at least a part of it, thereby forminga condensed stream while supplying at least a portion of the heating ofsteps (6) and (11); (16) fourth expansion means connected to said heatexchange means to receive said condensed stream and expand it to saidlower pressure, said fourth expansion means being further connected tosaid contacting and separating means to supply at least a portion ofsaid expanded condensed stream to said contacting and separating meansat a top feed position; and (17) control means adapted to regulate thequantities and temperatures of said feed streams to said contacting andseparating means to maintain the overhead temperature of said contactingand separating means at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 27.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into a first overhead vapor streamand said relatively less volatile fraction; the improvement wherein saidapparatus includes (1) first dividing means prior to said first coolingmeans to divide said gas stream into first and second streams; (2)second cooling means connected to said first dividing means to receivesaid first stream and cool it sufficiently to substantially condense it;(3) second dividing means connected to said second cooling means toreceive said substantially condensed first stream and divide it into atleast a first condensed portion and a second condensed portion; (4)second expansion means connected to said second dividing means toreceive said first condensed portion and expand it to said lowerpressure, said second expansion means being further connected to acontacting and separating means to supply said expanded first condensedportion to said contacting and separating means at a mid-column feedposition, said contacting and separating means being adapted to producea second overhead vapor stream and a bottom liquid stream; (5) thirdexpansion means connected to said second dividing means to receive saidsecond condensed portion and expand it to said lower pressure; (6) heatexchange means connected to said third expansion means to receive saidexpanded second condensed portion and heat it, said heat exchange meansbeing further connected to said contacting and separating means tosupply said heated expanded second condensed portion to said contactingand separating means at said mid-column feed position; (7) said firstcooling means being connected to said first dividing means to receivesaid second stream and cool it; (8) said first expansion means beingconnected to said first cooling means to receive said cooled secondstream and expand it to said lower pressure, said first expansion meansbeing further connected to said contacting and separating means tosupply said expanded cooled second stream to said contacting andseparating means at a first lower column feed position below saidmid-column feed position; (9) said distillation column being connectedto said contacting and separating means to receive at least a portion ofsaid bottom liquid stream; (10) said contacting and separating meansbeing further connected to said distillation column to receive at leasta portion of said first overhead vapor stream at a second lower columnfeed position below said mid-column feed position; (11) third dividingmeans connected to said contacting and separating means to receive saidsecond overhead vapor stream separated therein and divide it into atleast a first vapor portion and a second vapor portion; (12) said heatexchange means being further connected to said third dividing means toreceive at least a portion of said second vapor portion and heat it,thereafter discharging at least a portion of said heated second vaporportion as said volatile residue gas fraction; (13) vapor withdrawingmeans connected to said contacting and separating means to receive adistillation vapor stream from a region of said contacting andseparating device below said mid-column feed position and above saidfirst and second lower column feed positions; (14) combining meansconnected to said third dividing means and said vapor withdrawing meansto receive said first vapor portion and said distillation vapor streamand form a combined vapor stream; (15) compressing means connected tosaid combining means to receive said combined vapor stream and compressit to higher pressure; (16) said heat exchange means being furtherconnected to said compressing means to receive said compressed combinedvapor stream and cool it sufficiently to condense at least a part of it,thereby forming a condensed stream while supplying at least a portion ofthe heating of steps (6) and (12); (17) fourth expansion means connectedto said heat exchange means to receive said condensed stream and expandit to said lower pressure, said fourth expansion means being furtherconnected to said contacting and separating means to supply at least aportion of said expanded condensed stream to said contacting andseparating means at a top feed position; and (18) control means adaptedto regulate the quantities and temperatures of said feed streams to saidcontacting and separating means to maintain the overhead temperature ofsaid contacting and separating means at a temperature whereby the majorportions of the components in said relatively less volatile fraction arerecovered.
 28. In an apparatus for the separation of a gas streamcontaining methane, C₂ components, C₃ components, and heavierhydrocarbon components into a volatile residue gas fraction and arelatively less volatile fraction containing a major portion of said C₂components, C₃ components, and heavier hydrocarbon components or said C₃components and heavier hydrocarbon components, in said apparatus therebeing (a) a first cooling means to cool said gas stream under pressureconnected to provide a cooled stream under pressure; (b) a firstexpansion means connected to receive at least a portion of said cooledstream under pressure and expand it to a lower pressure, whereby saidstream is further cooled; and (c) a distillation column connected toreceive said further cooled stream, said distillation column beingadapted to separate said further cooled stream into a first overheadvapor stream and said relatively less volatile fraction; the improvementwherein said apparatus includes (1) said first cooling means beingadapted to cool said gas stream under pressure sufficiently to partiallycondense it; (2) separating means connected to said first cooling meansto receive said partially condensed gas stream and separate it into avapor stream and at least one liquid stream; (3) first dividing meansconnected to said separating means to receive said vapor stream anddivide it into first and second streams; (4) second cooling meansconnected to said first dividing means to receive said first stream andcool it sufficiently to substantially condense it; (5) second dividingmeans connected to said second cooling means to receive saidsubstantially condensed first stream and divide it into at least a firstcondensed portion and a second condensed portion; (6) second expansionmeans connected to said second dividing means to receive said firstcondensed portion and to expand it to said lower pressure, said secondexpansion means being further connected to a contacting and separatingmeans to supply said expanded first condensed portion to said contactingand separating means at a mid-column feed position, said contacting andseparating means being adapted to produce a second overhead vapor streamand a bottom liquid stream; (7) third expansion means connected to saidsecond dividing means to receive said second condensed portion andexpand it to said lower pressure; (8) heat exchange means connected tosaid third expansion means to receive said expanded second condensedportion and heat it, said heat exchange means being further connected tosaid contacting and separating means to supply said heated expandedsecond condensed portion to said contacting and separating means at saidmid-column feed position; (9) said first expansion means being connectedto said first dividing means to receive said second stream and expand itto said lower pressure, said first expansion means being furtherconnected to said contacting and separating means to supply saidexpanded second stream to said contacting and separating means at afirst lower column feed position below said mid-column feed position;(10) fourth expansion means connected to said separating means toreceive at least a portion of said at least one liquid stream and expandit to said lower pressure, said fourth expansion means being furtherconnected to said distillation column to supply said expanded liquidstream to said distillation column at a mid-column feed position; (11)said distillation column being connected to said contacting andseparating means to receive at least a portion of said bottom liquidstream; (12) said contacting and separating means being furtherconnected to said distillation column to receive at least a portion ofsaid first overhead vapor stream at a second lower column feed positionbelow said mid-column feed position; (13) third dividing means connectedto said contacting and separating means to receive said second overheadvapor stream separated therein and divide it into at least a first vaporportion and a second vapor portion; (14) said heat exchange means beingfurther connected to said third dividing means to receive at least aportion of said second vapor portion and heat it, thereafter dischargingat least a portion of said heated second vapor portion as said volatileresidue gas fraction; (15) vapor withdrawing means connected to saidcontacting and separating means to receive a distillation vapor streamfrom a region of said contacting and separating device below saidmid-column feed position and above said first and second lower columnfeed positions; (16) combining means connected to said third dividingmeans and said vapor withdrawing means to receive said first vaporportion and said distillation vapor stream and form a combined vaporstream; (17) compressing means connected to said combining means toreceive said combined vapor stream and compress it to higher pressure;(18) said heat exchange means being further connected to saidcompressing means to receive said compressed combined vapor stream andcool it sufficiently to condense at least a part of it, thereby forminga condensed stream while supplying at least a portion of the heating ofsteps (8) and (14); (19) fifth expansion means connected to said heatexchange means to receive said condensed stream and expand it to saidlower pressure, said fifth expansion means being further connected tosaid contacting and separating means to supply at least a portion ofsaid expanded condensed stream to said contacting and separating meansat a top feed position; and (20) control means adapted to regulate thequantities and temperatures of said feed streams to said contacting andseparating means to maintain the overhead temperature of said contactingand separating means at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 29.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into a first overhead vapor streamand said relatively less volatile fraction; the improvement wherein saidapparatus includes (1) first dividing means prior to said first coolingmeans to divide said gas stream into first and second streams; (2)second cooling means connected to said first dividing means to receivesaid first stream and cool it sufficiently to substantially condense it;(3) second dividing means connected to said second cooling means toreceive said substantially condensed first stream and divide it into atleast a first condensed portion and a second condensed portion; (4)second expansion means connected to said second dividing means toreceive said first condensed portion and to expand it to said lowerpressure, said second expansion means being further connected to acontacting and separating means to supply said expanded first condensedportion to said contacting and separating means at a mid-column feedposition, said contacting and separating means being adapted to producea second overhead vapor stream and a bottom liquid stream; (5) thirdexpansion means connected to said second dividing means to receive saidsecond condensed portion and expand it to said lower pressure; (6) heatexchange means connected to said third expansion means to receive saidexpanded second condensed portion and heat it, said heat exchange meansbeing further connected to said contacting and separating means tosupply said heated expanded second condensed portion to said contactingand separating means at said mid-column feed position; (7) said firstcooling means being connected to said first dividing means to receivesaid second stream, said first cooling means being adapted to cool saidsecond stream under pressure sufficiently to partially condense it; (8)separating means connected to said first cooling means to receive saidpartially condensed second stream and separate it into a vapor streamand at least one liquid stream; (9) said first expansion means beingconnected to said separating means to receive said vapor stream andexpand it to said lower pressure, said first expansion means beingfurther connected to said contacting and separating means to supply saidexpanded vapor stream to said contacting and separating means at a firstlower column feed position below said mid-column feed position; (10)fourth expansion means connected to said separating means to receive atleast a portion of said at least one liquid stream and expand it to saidlower pressure, said fourth expansion means being further connected tosaid distillation column to supply said expanded liquid stream to saiddistillation column at a mid-column feed position; (11) saiddistillation column being connected to said contacting and separatingmeans to receive at least a portion of said bottom liquid stream; (12)said contacting and separating means being further connected to saiddistillation column to receive at least a portion of said first overheadvapor stream at a second lower column feed position below saidmid-column feed position; (13) third dividing means connected to saidcontacting and separating means to receive said second overhead vaporstream separated therein and divide it into at least a first vaporportion and a second vapor portion; (14) said heat exchange means beingfurther connected to said third dividing means to receive at least aportion of said second vapor portion and beat it, thereafter dischargingat least a portion of said heated second vapor portion as said volatileresidue gas fraction; (15) vapor withdrawing means connected to saidcontacting and separating means to receive a distillation vapor streamfrom a region of said contacting and separating device below saidmid-column feed position and above said first and second lower columnfeed positions; (16) combining means connected to said third dividingmeans and said vapor withdrawing means to receive said first vaporportion and said distillation vapor stream and form a combined vaporstream; (17) compressing means connected to said combining means toreceive said combined vapor stream and compress it to higher pressure;(18) said heat exchange means being further connected to saidcompressing means to receive said compressed combined vapor stream andcool it sufficiently to condense at least a part of it, thereby forminga condensed stream while supplying at least a portion of the heating ofsteps (6) and (14); (19) fifth expansion means connected to said heatexchange means to receive said condensed stream and expand it to saidlower pressure, said fifth expansion means being further connected tosaid contacting and separating means to supply at least a portion ofsaid expanded condensed stream to said contacting and separating meansat a top feed position; and (20) control means adapted to regulate thequantities and temperatures of said feed streams to said contacting andseparating means to maintain the overhead temperature of said contactingand separating means at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 30.In an apparatus for the separation of a gas stream containing methane,C₂ components, C₃ components, and heavier hydrocarbon components into avolatile residue gas fraction and a relatively less volatile fractioncontaining a major portion of said C₂ components, C₃ components, andheavier hydrocarbon components or said C₃ components and heavierhydrocarbon components, in said apparatus there being (a) a firstcooling means to cool said gas stream under pressure connected toprovide a cooled stream under pressure; (b) a first expansion meansconnected to receive at least a portion of said cooled stream underpressure and expand it to a lower pressure, whereby said stream isfurther cooled; and (c) a distillation column connected to receive saidfurther cooled stream, said distillation column being adapted toseparate said further cooled stream into a first overhead vapor streamand said relatively less volatile fraction; the improvement wherein saidapparatus includes (1) said first cooling means being adapted to coolsaid gas stream under pressure sufficiently to partially condense it;(2) separating means connected to said first cooling means to receivesaid partially condensed gas stream and separate it into a vapor streamand at least one liquid stream; (3) first dividing means connected tosaid separating means to receive said vapor stream and divide it intofirst and second streams; (4) first combining means connected to saidfirst dividing means and said separating means to receive said firststream and at least a portion of said at least one liquid stream andform a combined stream; (5) second cooling means connected to said firstcombining means to receive said combined stream and cool it sufficientlyto substantially condense it; (6) second dividing means connected tosaid second cooling means to receive said substantially condensedcombined stream and divide it into at least a first condensed portionand a second condensed portion; (7) second expansion means connected tosaid second dividing means to receive said first condensed portion andto expand it to said lower pressure, said second expansion means beingfurther connected to a contacting and separating means to supply saidexpanded first condensed portion to said contacting and separating meansat a mid-column feed position, said contacting and separating meansbeing adapted to produce a second overhead vapor stream and a bottomliquid stream; (8) third expansion means connected to said seconddividing means to receive said second condensed portion and expand it tosaid lower pressure; (9) heat exchange means connected to said thirdexpansion means to receive said expanded second condensed portion andheat it, said heat exchange means being further connected to saidcontacting and separating means to supply said heated expanded secondcondensed portion to said contacting and separating means at saidmid-column feed position; (10) said first expansion means beingconnected to said first dividing means to receive said second stream andexpand it to said lower pressure, said first expansion means beingfurther connected to said contacting and separating means to supply saidexpanded second stream to said contacting and separating means at afirst lower column feed position below said mid-column feed position;(11) fourth expansion means connected to said separating means toreceive any remaining portion of said at least one liquid stream andexpand it to said lower pressure, said fourth expansion means beingfurther connected to said distillation column to supply said expandedliquid stream to said distillation column at a mid-column feed position;(12) said distillation column being connected to said contacting andseparating means to receive at least a portion of said bottom liquidstream; (13) said contacting and separating means being furtherconnected to said distillation column to receive at least a portion ofsaid first overhead vapor stream at a second lower column feed positionbelow said mid-column feed position; (14) third dividing means connectedto said contacting and separating means to receive said second overheadvapor stream separated therein and divide it into at least a first vaporportion and a second vapor portion; (15) said heat exchange means beingfurther connected to said third dividing means to receive at least aportion of said second vapor portion and heat it, thereafter dischargingat least a portion of said heated second vapor portion as said volatileresidue gas fraction; (16) vapor withdrawing means connected to saidcontacting and separating means to receive a distillation vapor streamfrom a region of said contacting and separating device below saidmid-column feed position and above said first and second lower columnfeed positions; (17) second combining means connected to said thirddividing means and said vapor withdrawing means to receive said firstvapor portion and said distillation vapor stream and form a combinedvapor stream; (18) compressing means connected to said second combiningmeans to receive said combined vapor stream and compress it to higherpressure; (19) said heat exchange means being further connected to saidcompressing means to receive said compressed combined vapor stream andcool it sufficiently to condense at least a part of it, thereby forminga condensed stream while supplying at least a portion of the heating ofsteps (9) and (15); (20) fifth expansion means connected to said heatexchange means to receive said condensed stream and expand it to saidlower pressure, said fifth expansion means being further connected tosaid contacting and separating means to supply at least a portion ofsaid expanded condensed stream to said contacting and separating meansat a top feed position; and (21) control means adapted to regulate thequantities and temperatures of said feed streams to said contacting andseparating means to maintain the overhead temperature of said contactingand separating means at a temperature whereby the major portions of thecomponents in said relatively less volatile fraction are recovered. 31.The improvement according to claim 21, 22, 23, 24, or 25 wherein saidvapor withdrawing means is connected to said distillation column toreceive said distillation vapor stream from a region of saiddistillation column below said top feed position and above said uppermid-column feed position.
 32. The improvement according to claim 21, 22,23, 24, or 25 wherein said vapor withdrawing means is connected to saiddistillation column to receive said distillation vapor stream from aregion of said distillation column below said mid-column feed position.33. The improvement according to claim 26, 27, 28, 29, or 30 whereinsaid vapor withdrawing means is connected to said contacting andseparating means to receive said distillation vapor stream from a regionof said contacting and separating means below said top feed position andabove said mid-column feed position.
 34. The improvement according toclaim 26, 27, 28, or 29 wherein (1) a fourth dividing means is connectedto said distillation column to receive said first overhead vapor streamand divide it into said distillation vapor stream and a seconddistillation vapor stream; (2) said contacting and separating device isadapted to be connected to said fourth dividing means to receive saidsecond distillation vapor stream at said second lower column feedposition; and (3) said combining means is adapted to be connected tosaid fourth dividing means to receive said distillation vapor stream.35. The improvement according to claim 30 wherein (1) a fourth dividingmeans is connected to said distillation column to receive said firstoverhead vapor stream and divide it into said distillation vapor streamand a second distillation vapor stream; (2) said contacting andseparating device is adapted to be connected to said fourth dividingmeans to receive said second distillation vapor stream at said secondlower column feed position; and (3) said second combining means isadapted to be connected to said fourth dividing means to receive saiddistillation vapor stream.
 36. The improvement according to claim 21,22, 23, 24, or 25 wherein said heated expanded second condensed portionis supplied to said distillation column at a second upper mid-columnfeed position.
 37. The improvement according to claim 31 wherein saidheated expanded second condensed portion is supplied to saiddistillation column at a second upper mid-column feed position.
 38. Theimprovement according to claim 32 wherein said heated expanded secondcondensed portion is supplied to said distillation column at a secondupper mid-column feed position.
 39. The improvement according to claim26, 27, 28, 29, 30, or 35 wherein said heated expanded second condensedportion is supplied to said contacting and separating device at a secondmid-column feed position.
 40. The improvement according to claim 33wherein said heated expanded second condensed portion is supplied tosaid contacting and separating device at a second mid-column feedposition.
 41. The improvement according to claim 34 wherein said heatedexpanded second condensed portion is supplied to said contacting andseparating device at a second mid-column feed position.